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United States Patent |
6,108,291
|
Ono
,   et al.
|
August 22, 2000
|
Optical disc apparatus accessing method and system therefor
Abstract
There are provided a plurality of information recording surfaces to be
reproduced on one side of an optical disc to be reproduced, and when
accessing control of an optical pickup over a plurality of recording
layers is performed, first, a beam focal point of the optical pickup is
moved using a moving device to the recording layer on which target
information is recorded to thereby perform switching processing of
information recording layers during reproduction, after which accessing
control of the optical pickup is performed using control processing
circuit similar to the access between the same recording layers, and with
respect to the pausing operation, in a layer in which information is
recorded from the inner circumference to the outer circumference, one
track jumping is repeated toward the inner circumference, while in a layer
in which information is recorded from the outer circumference to the inner
circumference, one track jumping is repeated toward the outer
circumference.
Inventors:
|
Ono; Kazuhiko (Yokohama, JP);
Ikeda; Eiji (Yokohama, JP);
Minoda; Hiroshi (Yokohama, JP);
Fukushima; Akio (Yokohama, JP);
Shioyama; Hiroaki (Yokohama, JP);
Inoue; Shigeki (Fujisawa, JP)
|
Assignee:
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Hitachi, Ltd. (Tokyo, JP)
|
Appl. No.:
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394600 |
Filed:
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September 13, 1999 |
Foreign Application Priority Data
Current U.S. Class: |
369/47.11; 369/44.28 |
Intern'l Class: |
G11B 007/00 |
Field of Search: |
369/94,44.27,44.28,32,54,58,47
|
References Cited
U.S. Patent Documents
5255262 | Oct., 1993 | Best et al. | 369/275.
|
5428597 | Jun., 1995 | Satoh et al. | 369/94.
|
5608715 | Mar., 1997 | Yokogawa et al. | 369/94.
|
5881032 | Mar., 1999 | Ito et al. | 369/32.
|
Primary Examiner: Tran; Thang V.
Attorney, Agent or Firm: Beard, Jr.; R. William
Frohwitter
Parent Case Text
This application is a divisional of U.S. application Ser. No. 08/888,469,
filed Jul. 7, 1997, now U.S. Pat. No. 6,002,655.
Claims
What is claimed is:
1. An accessing method for an optical disc apparatus for
recording/reproducing an optical disc on one side of which are provided
plural layers of information recording surfaces, the method comprising the
steps of:
when at least one information recording layer among said plural layers of
information recording layers is recorded in the OTP (Opposite Track Path)
type, recording the OTP type on said information recording layer;
reproducing the information of said OTP type information recording layer;
and
upon receipt of command of pausing during the execution of said
reproduction, performing the pausing operation by jumping an optical
pickup by one track toward the outer circumference of the disc at the
pause designated position.
2. An accessing method for an optical disc apparatus for
recording/reproducing an optical disc on one side of which are provided
plural layers of information recording surfaces, said method comprising
the steps of:
when at least one information recording layer among said plural layers of
information recording layers is recorded in the OTP (Opposite Track Path)
type, recording the OTP type on said information recording layer;
when at least another information recording layer among said plural layers
of information recording layers is recorded in the PTP (Parallel Track
Path) type, recording the PTP type on said information recording layer;
reproducing information of the information recording layer of either of
said types;
upon receipt of command of pausing during the execution of said
reproduction and when said information recording layer is recorded in the
OTP type, performing the pausing operation by jumping an optical pickup by
one track toward the outer circumference of the disc at the pause
designated position; and
upon receipt of command of pausing during the execution of said
reproduction and when said information recording layer is recorded in the
PTP type, performing the pausing operation by jumping an optical pickup by
one track toward the inner circumference of the disc at the pause
designated position.
3. An accessing system for an optical disc apparatus for
recording/reproducing an optical disc on one side of which are provided
plural layers of information recording surfaces, comprising:
when at least one information recording layer among said plural layers of
information recording layers is recorded in the OTP (Opposite Track Path)
type, means for recording the OTP type on said information recording
layer;
means for reproducing the information of said OTP type information
recording layer; and
upon receipt of command of pausing during the execution of said
reproduction, means for performing the pausing operation by jumping an
optical pickup by one track toward the outer circumference of the disc at
the pause designated position.
4. An accessing system for an optical disc apparatus for
recording/reproducing an optical disc on one side of which are provided
plural layers of information recording surfaces, comprising:
when at least one information recording layer among said plural layers of
information recording layers is recorded in the OTP (Opposite Track Path)
type, means for recording the OTP type on said information recording
layer;
when at least another information recording layer among said plural layers
of information recording layers is recorded in the PTP (Parallel Track
Path) type, means for recording the PTP type on said information recording
layer;
means for reproducing information of the information recording layer of
either of said types;
upon receipt of command of pausing during the execution of said
reproduction and when said information recording layer is recorded in the
OTP type, means for performing the pausing operation by jumping an optical
pickup by one track toward the outer circumference of the disc at the
pause designated position; and
upon receipt of command of pausing during the execution of said
reproduction and when said information recording layer is recorded in the
PTP type, means for performing the pausing operation by jumping an optical
pickup by one track toward the inner circumference of the disc at the
pause designated position.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical disc apparatus accessing method
and system therefor capable of reproducing an optical disc on one surface
of which are provided plural layers of information recording surfaces.
2. Description of the Prior Art
In the optical disc as a recording medium, laser discs (LD) have been
extensively popularized as media in which plural layers of information
recording surfaces are provided. In these recording media, each layer of
information recording surface is present on both surfaces of the media in
terms of physical construction. Therefore, in the case where information
recording layers to be reproduced need be switched, it is general that the
disc is inverted or changed.
With the recent trend of larger capacity of data for a computer and
practical use of recording and reproducing of digital moving picture
information, it has been demanded to make the optical disc higher
recording density. The specification of a large capacity optical disc such
as DVD (Digital Versatile Disc) has been proposed, and an optical disc
such as a dual-layer disc has been standardized in addition to a
conventional information recording of a one-side single layer. Since these
optical discs have a dual-layer information recording layer on one side,
there is necessary a reproducing method different from the conventional
reproduction of single layer disc depending on switching of an information
recording layer to be reproduced, and the form of information recorded and
how to use it. One method is an accessing method and the other is a
pausing (temporary stop) method.
In the optical disc, in the case where an optical pickup is accessed to a
recording position of read target information on the same information
recording layer in order to realize the high speed access, normally,
present position information recorded in the disc is first read to obtain
the present position of the optical pickup. Then, a target position is
obtained from a logic or physical address of read target information.
These two positions are converted from an information recording format of
the disc into physical position information, the distance on a disc plane
between the two points is obtained, and the optical pickup is accessed to
the target position by means for controlling a slider on which the optical
pickup is loaded.
However, in the case of the optical disc having a plurality of information
recording layers on one side, there is taken the procedure such that in
the case where read target information is present on the other information
recording layer, the track positions between the information recording
layers are not always coincided, and the optical pickup is moved to the
target position on the basis of position information of the information
recording layer now being reproduced, after which the optical pickup is
moved to the target information recording layer. This procedure has a
problem in that accessing cannot be made to the target position at high
speeds and accurately.
In addition, the one-side dual-layer disc of DVD includes two kinds, one
being a parallel track path (hereinafter referred to as PTP) in which the
recording path of the first layer is the same as that of the second layer
as shown in FIG. 3 (1), and the other being an opposite track path
(hereinafter referred to as OTP) in which the recording path of the first
layer is reversed to that of the second layer as shown in FIG. 3 (2). In
case of the OTP, the physical address of the second layer is provided
without direct relation with that of the first layer, and therefore,
accessing to the other information layer is impossible on the basis of the
position information of the information recording layer now being
reproduced.
Also, with respect to the pausing (temporary stop) operation, there is a
problem in that the pausing is not obtained in the second layer of the
disc of OTP in the state of the operation of the conventional reproduction
of one-side single disc.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide, in the reproduction of
these discs having a plurality of recording layers, a method for carrying
out an access control of an optical pickup accurately, at high speeds and
easily, a method for carrying out a pausing operation accurately
irrespective of kinds of discs and a system therefor.
For achieving the aforementioned object, according to the present
invention, there is provided an accessing method for an optical disc
apparatus for recording/reproducing an optical disc on one side of which
are provided plural layers of information recording surfaces and system
therefor, the method comprising:
recording/reproducing information on at least one information recording
layer among said plural layers of information recording layers, and
switching the information recording layer for information to be
recorded/reproduced during the information recording/reproducing.
More specifically, according to the present invention, in starting the
access control of an optical pickup over a plurality of recording layers,
first, a beam focal point of the optical pickup is moved by using a moving
means to a recording layer in which target information is recorded to
switch information recording layers during reproduction, and after this,
the distance on a disc plane between two points is obtained from a present
position of the optical pickup on the information recording layer after
movement and a target position of read information, using a control
processing means similar to the access between the same recording layers
to perform the access control of the optical pickup. Further, according
to-the present invention, with respect to the pausing operation, whether
or not a disc during reproduction is one-side dual-disc is stored in
advance by an optical disc reproducing apparatus, and when instructions
for pausing operation are given at the time of reproduction of the second
layer of the OTP disc, the track jump direction of the pickup is reversed
to that of the first layer.
The foregoing and other objects, advantages, manner of operation and novel
features of the present invention will be understood from the following
detailed description when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an optical disc apparatus forming the
constitutional requirement of the present invention according to a first
embodiment of the present invention;
FIG. 2 is view schematically showing the construction of a DVD dual-layer
disc used in the present embodiment;
FIGS. 3(a) and 3(b) are respectively views schematically showing a physical
sector layout of DVD dual-layer disc and address information construction
used in the present embodiment;
FIG. 4 is a flowchart showing the flow of a switching process of
reproducing information recording layer in one embodiment of the present
invention;
FIG. 5 is a flowchart showing the flow of an access controlling process of
an optical pickup in one embodiment of the present invention;
FIG. 6 is a flowchart showing the flow of conventional pausing operation;
and
FIG. 7 is a flowchart showing the flow of conventional pausing operation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be explained hereinafter with reference to one
embodiment shown in the drawings.
FIG. 1 is a block diagram of an optical disc apparatus forming the
constitutional requirement of the present invention according to a first
embodiment of the present invention. The present optical disc reproducing
apparatus is composed of, other than those shown here, a decoder block for
reproducing, demodulating, error-correcting signals for decoding
reproduced data, a system control block for controlling the entire optical
disc apparatus, an interface block for the interface with external
information processing equipment, an encoder block for modulation and
error-correction for recording data, etc. The blocks not directly relating
to the present invention out of the above-described blocks will be omitted
in their explanation and drawings.
First, the functions of the blocks shown will be roughly explained below.
An optical disc 1 is an optically readable information storage medium such
as a compact disc (CD), a digital versatile disc (DVD), etc. Information
is recorded in a signal recording surface at a concave portion called a
pit.
An optical pickup 2 is to reproduce information from the optical disc 1 and
comprises a semiconductor laser and optical parts not shown, a focus
actuator 3, a tracking actuator 4, and a light detector 5. Light departed
from the semiconductor laser is focussed at a signal recording surface of
the optical disc 1 to form an optical spot. Since the quantity of light
reflected from the optical spot changes due to the presence or absence of
pit, the change of the quantity of light can be detected as a signal to
reproduce the signal.
The light detector 5 is to convert the change in the quantity of light
reflected from the optical disc 1 into a current signal. An output of the
light detector 5 is converted into a voltage signal by a current-voltage
converter circuit 6, which voltage signal is transmitted to a focus error
detection circuit 7 and a tracking servo circuit 8. A focus error signal
71 detected by the focus error detection circuit 7 is applied to the focus
actuator 3 via a phase compensation circuit 9, a switch 10 and a drive
circuit 11 to form a focus servo loop for controlling an objective lens 12
in a focussing direction.
A search signal generation circuit 13 is a circuit for generating a search
signal 15 according to a focus search control signal 14. The search signal
15 is transmitted to the drive circuit 11 and applied to the focus
generator 3 whereby the objective lens 12 can be moved in the focussing
direction separately from the focus servo loop.
The switch 10 is switched according to the state of a focus switching
signal 16 to switch the switch 10 so that an output of the phase
compensation circuit 9 is transmitted to the drive circuit 11 whereby the
operation of the focus servo loop can start.
The tracking servo circuit 8 comprises a tracking error detection circuit,
a phase compensation circuit and the like, and an output signal is applied
to the tracking actuator 4 via a drive circuit 17 to form a tracking servo
loop for controlling the objective lens 12 in a tracking direction.
In the switch 18, the tracking servo loop is opened by a tracking control
switching signal 19, and the objective lens 12 can be moved in the
tracking direction by an output signal of a tracking actuator motion
signal generation circuit 20.
A slide motor 21 is to move the optical pickup 2. Normally, an output
signal of the tracking servo circuit 8 is transmitted to a drive circuit
23 via a slide motor servo circuit 22 to form a slide motor servo loop. In
the case where the optical pickup is moved for the access operation or the
like, a switch 25 is switched by a slide motor control switching signal
24, and a controller 27 outputs a slide motor control signal 28 to a slide
motor motion signal generation circuit 29 according to speed and position
information obtained by an output signal of a rotary encoder 26 to drive a
slide motor 21 via the drive circuit 23.
Next, one example of an optical disc on one side of which are provided two
layers of information recording layers will be explained. The present
optical disc reproducing apparatus reproduces CD, DVD single layer, and
DVD dual layer discs. The dual disc of DVD will be explained below as an
example.
FIG. 2 shows the construction of a DVD dual-layer disc.
The DVD dual-layer disc as two information recording layers arranged on one
side of the disc at intervals of approximately 55 .mu.m thickness-wise of
the disc. These information recording layers are normally formed
separately and mechanically pasted together.
In FIG. 2, a first layer 1 is a translucent recording film, and a second
layer 2 is a reflecting film formed of aluminum vapor deposition or the
like. The reproduction of the dual-layer disc is carried out, as shown in
FIG. 2, by irradiating a laser beam from the first layer 1 side and moving
the objective lens 12 in the direction at right angles to the disc to form
a focal point to the first layer 1 and the second layer 2.
FIGS. 3(a) and 3(b) are respectively views schematically showing a physical
sector layout of DVD dual-layer disc and address information construction.
FIG. 3(a) shows a parallel track path (PTP). A physical sector of the same
address, which is not related to address information and incremented from
the inner circumference to the outer circumference of the disc, is present
in each information recording layer between a physical sector on the layer
0 (first layer) and a physical sector on the layer 1 (second layer).
FIG. 3(b) shows an opposite track path (OTP). Address information of a
start physical sector on the layer 1 (second layer) is represented by
address information whose each bit being inverted of address information
of a final physical sector on the layer 0 (first layer), and the address
information of the layer 1 (second layer) is incremented from the outer
circumference to the inner circumference of the disc and recorded. That
is, the address information of the layer 0 (first layer) is incremented
from the inner circumference to the outer circumference of the disc
whereas the address information of the layer 1 (second layer) is
incremented from the outer circumference to the inner circumference of the
disc.
In the DVD disc, information of one side single-layer disc, one side
dual-layer disc, disc of PTP or disc of OTP is recorded as index
information of disc in a control data area of the disc, and information of
the layer 0 (first layer) of the layer 1 (second layer) is recorded in the
sector address.
Accordingly, in the optical disc reproducing apparatus, it is possible to
know what disc is contained by reading the index information, and it is
possible to carry out the special reproduction conveniently by storing
whether the disc being reproduced is the disc of PTP or the disc of OTP in
the optical disc reproducing apparatus.
In what disc of PTP shown in FIG. 3(a) and of OTP shown in FIG. 3(b), in
the case where accessing between and over information recording layers so
that the optical pickup is moved from the physical sector A present on the
layer 0 (first layer) to the physical sector B present on the layer 1
(second layer), the movement of the optical pickup in a direction of
thickness of the disc for switching the information recording layer in
which the optical spot forms a focal point is necessary in addition to the
movement of the optical pickup in a radial direction of the disc in the
prior art.
The procedure for switching an information recording layer to be reproduced
in the present optical disc apparatus will be explained below. In the
ensuing procedure, an example will be explained in which the processing of
CPU which functions as a system controller is accomplished by soft-ware.
FIG. 4 is a flowchart showing the flow of a switching process of
reproducing information recording layer.
In 401, confirmation is made by information in the sector address whether
or not the information recording layer being now reproduced while the
objective lens of the optical pickup forms a focal point is the first
layer or the second layer. In 402, confirmation is made of the recording
layer of the target information.
As a result of the processing in 401 and 402, if judgement is made that the
target recording layer is another layer, the servo loop such as the focus
servo, tracking servo, etc. for maintaining a focal point of the optical
spot in an intended position of the information recording layer of the
disc is set to off, in 404.
After this, in 405, a focus search control signal for driving the objective
lens toward the focusing direction of the target information recording
layer starts to be delivered. As a result, a focus error signal starts to
be output as the focal point of the optical spot gradually moves close to
the adjacent information recording layer.
In 406, the focus search control signal is continued to deliver till
exceeding a preset judging level while monitoring the focus error signal.
After exceeding the judging level, in 407, a signal reverse in phase to the
drive signal applied in 405 is output to the focus search control signal
for the drawing stabilization of the thereafter focus servo loop to apply
a brake to the focus actuator.
In 408, the zero cross point of the focus error signal is detected to
thereby judge to be reached to the adjacent information recording layer.
Thereafter, in 409, the switch is switched to set the focus servo loop to
on, and to set other servo loops to on sequentially.
Now, in the optical disc in which two information recording layers are
actually provided on one side, accessing over the information recording
layers will be explained.
Generally, in the optical discs such as CD and DVD, the procedure is
employed in which the logical present position and target position at the
start of accessing are converted into the physical position on the disc,
the difference thereof is obtained to calculate the distance on the disc
plane between relative two points, and the optical pickup is moved to the
target position at high speeds without reading the position information
recorded in the moving disc using control means for the slider on which
the optical pickup is loaded.
One example of the method for converting the present position and the
target position into the physical position will be explained. Let R0 (m)
be the radius from the center of the disc of the sector number S0 as a
reference on the disc, CLV (m/s) be the linear speed when the information
of disc is recorded, TP (m) be the track pitch, and T0 be the time
required to reproduce 1 sector. Then, the relation with the radius R1 (m)
from the disc center of the sector number S1 present on the same
information recording layer can be expressed by
R12=(CLV.multidot.TP.multidot.T0(S1-S0)/.pi.)+R02
In the case of the dual-disc, the information recording layers are
different in the linear speed and the track pitch in terms of forming the
disc, it is therefore necessary to use the above-described formula every
information recording layer in which sector is recorded.
In the case where accessing is carried out over the information recording
layers, in the disc of PTP, the physical sector is provided from the inner
circumference to the outer circumference of the disc in both the layer 0
(first layer) and the layer 1 (second layer). So, there is a method
comprising: moving the target distance on the basis of the information of
the information recording layer now being reproduced, approaching to the
target sector while reading the present position information recorded in
the information recording layer being reproduced, and after this,
accessing to the target sector over the information recording layers.
However, since the layer 0 and the layer 1 are not always coincided in the
track pitch and the linear speed, the wasteful access time to the final
target sector occurs.
Further, in the disc of OTP, the layer 0 is totally different in the
physical sector from that of the layer 1, and it is impossible to access
to the target sector of the other information recording layers on the
basis of the information of the information recording layer now being
reproduced.
In the present embodiment, the aforementioned problems are solved by the
following processing.
FIG. 5 is a flowchart showing the flow of an access controlling process of
an optical pickup according to the present invention.
In the present embodiment, first, in 501, confirmation is made of the
position of the optical pickup by reading the present position information
recorded in the optical disc.
Then, in 502, judgement is made whether or not the recording position of
the target information subjected to accessing is the same as the present
information recording layer.
When the information recording layer is not the same, in 503, the beam
focal point of the optical pickup is moved to the target information
recording layer by the focus moving means previously explained with
reference to FIG. 4.
After movement, in 504, confirmation is made of the present position of the
optical pickup on the information recording layer after movement by the
processing similar to that of 501.
In 505 and 506, the present position and the target position are converted
to the physical position on the disc.
In 507, the distance on the disc plane between the relative two points is
calculated from the physical positions of the present position and the
target position obtained by the above described methods. In 508, the
optical pickup is moved to the target position at high speeds, without
reading the position information recorded in the moving disc, using the
control means of the slider on which the optical pickup is loaded.
After movement, in 509, the optical pickup is accessed to the target
information recording position while confirming the position information
recorded in the disc.
In the above-described series of processings, also in the case of accessing
over the information recording layers, accessing is carried out merely
adding the processings of 502, 503 and 504, so that the processing means
similar to the conventional accessing processing in the same information
recording layer after 505 can be used, thus enabling the high speed
accessing and enabling processing easily.
The pausing operation according to the present invention will be explained
hereinafter with reference to FIGS. 6 and 7. FIG. 6 is a flowchart of the
pausing operation heretofore used in CD and LD. FIG. 7 is a flowchart of
the pausing operation according to the present invention. In both CD and
LD, information is recorded along the spiral signal track from the inner
circumference to the outer circumference of the disc. In FIG. 6, upon
command of the pausing operation, in 601, "Jump by one track toward the
inner circumference, at the pause designated position." whereby the
pausing is realized. In 602, this operation is repeated till receipt of
the end of pause command. Also in the single-layer disc of DVD and the PTP
disc, pausing can be realized in FIG. 6. However, in the layer 1 (second
layer) of the OTP disc, the FIG. 6 method rapidly progresses, failing to
provide the pausing operation.
In FIG. 7, in the optical disc reproducing apparatus, the presence of the
OTP disc is read from the index information. Upon receipt of command of
pausing operation, first, in 703, "OTP disc ?" is checked, and in 704,
"Layer 1 (second layer) ?" is checked from the sector address being
reproduced. Only at the time of the layer 1 (second layer) in the OTP
disc, "Jump by one track toward the outer circumference, at the pause
designated position" in 705 whereby the pausing operation is realized.
While in the embodiments according to the present invention, a description
has been made of the case of the dual-layer disc, it is to be noted that
needless to say, the accessing method and the pausing method according to
the present invention can be applied to the disc reproducing apparatus
having a plurality of information recording layers such as three layers,
four layers, etc.
According to the present invention, in the optical disc apparatus having a
plurality of information recording surfaces to be reproduced on one side
of the optical disc and which is necessary to switch these information
recording layers to be reproduced during the operation, even in the case
where the recording position of intended information is provided other
than the information recording layer now being reproduced, it is possible
to carry out the access control of the optical pickup using the control
processing means similar to the access between the same recording layers
accurately, at high speeds and relatively easily, and further in both PTP
disc and OTP disc, the pausing operation can be realized.
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